The move follows a blow to HTC in July when the ITC issued an initial determination that HTC infringed two patents, based on a different complaint filed by Apple. The determination is now being reviewed by a larger panel of ITC judges, who can uphold or reject it. If they uphold it, HTC will be banned from importing certain phones to the U.S.

The ITC is also investigating a third Apple complaint against HTC as well as an HTC complaint against Apple.

In addition to the ITC complaints, the companies have also filed patent-infringement lawsuits against each other.

The disputes are part of a larger attack on Android being waged by Apple, Microsoft and others. Apple has also sued Samsung and has spurred the ban of Samsung Android tablets in Australia and now Europe. Microsoft has convinced HTC to pay it licensing fees for each Android phone it makes. In addition, Oracle is battling Google for allegedly infringing Oracle's Java patents and copyrights in Android.